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Donut-shaped high-dose configuration for proton beam radiation therapy.

Rutz HP, Lomax AJ

Division of Radiation Medicine, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland. hanspeter.rutz@psi.ch

BACKGROUND: The authors report on the conception and first clinical application of a donut-shaped high-dose configuration for proton therapy (PT). This approach allows one to intensify target volume dose coverage for targets encompassing a critical, dose-limiting structure--like here, the cauda equina--, whilst delivering minimal dose to other healthy structures surrounding the target, thereby reducing the integral dose. METHODS AND RESULTS: Intensity-modulated PT methods (IMPT) for spot scanning were applied to create and deliver a donut-shaped high-dose configuration with protons, allowing treating > 75% of the target with at least 95% of the prescribed dose of 72.8 CGE, whilst restricting dose to the cauda equina to 60-65 CGE. Integral dose was lower by a factor of 3.3 as compared to intensity-modulated radiotherapy with photons (IMXT). CONCLUSION: IMPT and spot scanning technology allow a potentially clinically useful approach which is also applicable to spare other critical structures passing through a target volume, including spinal cord, optic nerves, chiasm, brain stem, or urethra.

Published 20 January 2005 in Strahlenther Onkol, 181(1): 49-53.
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